The present invention relates generally to lipstick containers, and more particularly to lipstick containers having mechanical mechanisms for manipulating their associate lipstick masses longitudinally within the containers between extended and retracted positions.
Lipstick containers having mechanisms for manipulating their associated lipstick masses are well-known in the art. The prior art containers generally have a main inner body member with a finger engaging knob or base portion at one end thereof and a tubular sleeve at the other end thereof. Extending longitudinally in the tubular sleeve are a pair of diametrically opposed elongated slots with locking portions at their terminal ends.
Mounted within the tubular sleeve is a cup adapted to receive the lipstick mass and having a pair of diametrically opposed, outwardly extending posts captured in the pair of slots in the tubular sleeve. The posts are also captured in a pair of helical or spiral grooves formed in the inner wall of an outer sleeve which surrounds the tubular sleeve of the inner body member. The inner body member and the outer sleeve are mechanically retained to one another at their upper ends by a conventional lip and groove arrangement which permits relative rotational movement therebetween.
In operation, relative rotation between the inner body member and the outer sleeve forces the captured posts of the cup member to follow both the longitudinal slots of the inner body member and the helical grooves of the outer sleeve to move the cup element longitudinally in the inner body member, alternatively, between its retracted locked position completely within the inner body member and its protracted locked position extending partially outside the inner body member. In its retracted locked position, the posts of the cup member are located within the lower locking portions (adjacent the knob or base portion) of the longitudinal slots; the cup being thereby inhibited from longitudinal movement during transportation and handling of the lipstick container. In its protracted locked position, inadvertent downward movement of the cup is inhibited during both the loading of the lipstick mass into the container during the assembly process and the application of associated lipstick onto a user's lips.
One of the problems which has been encountered in the use and manufacture of such containers is wide, undesirable variations in the torque required to control the relative rotation of the inner body member and the outer sleeve to drive the cup element between the retracted and protracted positions.
Torque for lipstick container is generally measured in inch-ounces with the ideal range of acceptability being two (2) to six (6) inch ounces. To achieve this range in the prior art lipstick containers, a variety of methods have been used including manufacturing the cup element to have an outer diameter slightly larger than the inner diameter of the main body member whereby the cup member tends to resist longitudinal movement within the inner body member. In practice, due to manufacturing inaccuracies, such as encountering non-uniform inner diameters of the main body member as the cup element moves axially therethrough, the torque found in the prior art devices tends to range from one to thirteen inch-ounces and can vary dramatically over the stroke of the cup element between its retracted and protracted positions. Oftentimes, the containers with torques at the upper end of this range are nearly inoperable and must be rejected and discarded as having unacceptably high torques.
Other prior art methods for controlling torque, such as those disclosed in U.S. Pat. No. 4,514,102 provide a smoothness of rotational action However, the design disclosed in the U.S. Pat. No. 4,514,102 patent has the undesirable quality of incorporating a cylindrical collar which is relatively rigid and unable to adequately accommodate large variations in sizes due to the tolarances inherent in the manufacturing process.
Another prior art design, U.S. Pat. No. 4,792,251 produces a smooth operating mechanism but requires an additional element, i.e. a friction ring, which adds to the expense in manufacturing and assembling the container.
It is a problem underlying the present invention to provide a lipstick container which utilizes a limited number of parts while still providing an ultrasmooth, operating mechanism.
It is an object of the present invention to provide a lipstick container which overcomes the limitations and failings of the prior art designs.
It is a further object of the present invention to provide a lipstick container which has a uniform torque throughout the length of its stroke to create an ultrasmooth operating mechanism.
It is a still further object of the present invention to provide a lipstick container which is relatively inexpensive to fabricate and assemble.